High frequency television antenna



June 6, 1961 J. F. GUERNSEY HIGH FREQUENCY TELEVISION ANTENNA 3Sheets-Sheet 1 Filed Feb. 13, 1958 June 6, 1961 J. F. GUERNSEY HIGHFREQUENCY TELEVISION ANTENNA 3 Sheets-Sheet 2 Filed Feb. 13, 1958 June6, 1961 J. F. GUERNSEY HIGH FREQUENCY TELEVISION ANTENNA 5 Sheets-Sheet3 Filed Feb. 13, 1958 United States Patent 2,987,723 HIGH FREQUENCYTELEVISION ANTENNA John F. Guernsey, Griggsville, 111., assignor to TrioManufacturing Co., Griggsville, 11]., a corporation of Illinois FiledFeb. 13, 1958, Ser. No. 715,043 22 Claims. (Cl. 343-813) This inventionrelates generally to high frequency antennas especially intended for useover the present television frequency spectrum, but the invention is notlimited to such frequencies.

The invention herein is specifically directed to improvement of thestructures shown and described in U.S. Patent 2,772,413 issued November27, 1956, to the applicant herein and to Arthur E. Vail and assigned tothe assignee of this patent application. In that patent there wasdescribed and claimed a composite dipole which was resonant to severalfrequencies one of which was approximately a whole number multiple orharmonic of the other. The components which formed the composite dipolewere arranged in a horizontal plane and advantageous results wereachieved through the use of end-fire principles, through the electricaland mechanical connections of said elements, and the parasitic anddriven relationships therebetween.

Considerable success was achieved commercially in marketing antennaswhich were constructed in accordance with the principles of said patent,and this was especially true of multiple arrays of said compositedipoles, arranged along horizontal booms and stagger-tuned, that is tosay, arranged to be resonant at different frequencies over the entirespectrum in order to attempt to achieve substantially uniform gain forall frequencies in the high and low television bands. As well-known,these presently comprise a low band formed of channels 2 to 6 inclusivewhich encompass signals from 54 to 88 megacycles per second, and a highband formed of channels 9 to 13 inclusive which encompass signals from174 to 216 megacycles per second (hereinafter sometimes designated bythe abbreviation mcs.).

Obviously the principal object of this invention is to provide asubstantially improved antenna, not only with respect to the compositedipole, but in addition, with respect to the achievement of improvedarrays of driven elements utilizing the improved dipole, the dipole ofsaid US. patent, and other driven elements associated with variousparasitic elements and phasing means.

There were several reasons why it was believed that the fullcapabilities of the end fire composite dipole as described in said US.patent were not being used. It was found especially that when used byitself, a composite dipole resonant at channel 2, the low end of the lowband, did not give the optimum results at the extreme end of the highband, say at channels 11, 12 and 13. The requirements which complicatedthe likely solution to the problem included:

(a) Achieving an impedance as close to 300 ohms as possible.

(b) Improving the directivity for the high channels without destroyingthe gain of the low channels.

(c) Retaining the advantages of end-fire characteristics and thus notvarying from the basic dimensions and spacing of the high frequencyelements determined to be optimum.

(d) Arriving at the improved gain, directivity and impedance withoutproviding any complex mechanical structures diflicult and expensive toproduce and to set up.

(2) Evolving a composite dipole which is simple and capable of beingreadily folded, for storage and shipment.

Obviously an important object of the invention is the provision of acomposite dipole which solves the problem and meets the requirements.

A more specific discussion of the requirements and why meeting themcomprised a completely unobvious solution to the problem would bevaluable at this point. It will be recalled that this concerns theconstruction of a composite dipole for use in small antennas, perhaps byitself with several parasitics, or with a second driven element, eitherof similar structure or slightly dilferent. As will appear hereinafter,the solution was so excellent, that the structure applied to largeantennas which use two and three of these new composite dipoles givesgreatly improved results over the large antennas described in saidpatent.

A simple dipole has low impedance, and it requires additionalfolded-back elements to improve the impedance so that it approaches the300 ohms of the conventional two wire transmission line in use today.Thus this must be provided. The front to back spacing of the highfrequency elements used in an end-fire composite array according to theteachings of the said patent could not be substantially varied withoutadversely affecting the high frequency response, and when combined withthe folded diagonal members, the angle of the diagonal members waslimited to a certain amount by virtue of structure requirements. Thedesire to decrease the angle of the V-shaped configuration meant thatstructure had to be worked out which would enable the spacing of thehigh frequency elements to be substantially retained. Furthermore, thelow frequency aperture and response had to be preserved. The V-shapedelements were lengthened beyond the overall length of high frequencyelements, and a novel connection between the respective ends of theelements was provided.

It will thus be seen that through the retention of the basic structurewith folded V-shaped elements, the characteristics of a folded dipolewith its 300 ohm resistance were retained; the V-shape configurationenabled the high band directivity to be achieved with improvements alsoin the low channel response and the angle on of the V was made smallerthan deemed possible with the structure of the said patented antenna;through the novel construction, the V-shaped configuration was providedwithout materially upsetting or changing the front to rear spacing ofthe high frequency end-fire elements and without changing their overallcomposite length; and all of this was accomplished in a simple mannerand with structure enabling the folding of the antenna.

Objects of the invention comprise the provision of a composite dipolestructure using these novel arrangements and achieving the attributesnamed.

The structure providing for extension of the length of the V-shapeddipole beyond the ends of the effective high frequency end-fire elementsis achieved as a specific object of the invention, and also the swivelconnection between the halves of the V-shaped dipole and the ends of theend-fire elements is a structure of importance.

Many other objects will occur to those skilled in this art and theadvantages will become apparent with the descriptive details of thepreferred embodiments which are set forth hereinafter in connection withthe drawings.

In the said drawings there are illustrated two forms of the specificdipole of the invention herein as well as several antennas which combinethe said dipoles with other driven and parasitic elements but theinvention is capable of being embodied in many variants of these dipolesand the antennas illustrated. The drawings also include illustrations indiagrammatic form for explanatory purposes and for demonstrating thetheory of operation of the invention, but no limitations are intendedthereby.

The same reference numerals are used in different fig ures to illustrateor designate similar or equivalent elements or structural components.

In said drawings:

FIG. 1 is a diagrammatic top view of a composite dipole antennaconstructed according to US. Patent No. 2,772,413 showing the generalazimuth radiation pattern of gain thereof.

FIG. 2 is a diagrammatic view of the same antenna but showing only theso-called high band elements.

FIG. 3 is a diagrammatic view of a simple dipole antenna element showingthe radiation pattern thereof when operated on a harmonic thereof ofhigher frequency than that for which the element is a half wave antenna.

FIG. 4 is a diagrammatic view of the dipole of FIG. 3 together with itsradiation pattern in azimuth in which the antenna has been bent in onedirection to form a V configuration.

FIG. 5 is still another diagrammatic representation of an antenna, butthis view showing a composite of the elements of FIG. 4 and FIG. 2.

FIG. 6 is a top plan view of a composite dipole antenna assemblage ofgenerally elementary form, that is to say a single composite,constructed in accordance with the invention herein.

FIG. 6a is a sectional view along line 6a6a of FIG. 6 through a pivotalconnection taken in the direction indicated.

FIG. 7 is a fragmentary perspective view of a television antenna inwhich one of the active or driven elements thereof is constructed inaccordance with the invention, but comprises a modified form of theconstruction shown and described in connection with FIG 6 FIG. 7a is adiagrammatic representation of the antenna of FIG. 7 to show the generalarrangement thereof n e t o o he Pa FIG. 8 is adiagrammaticrepresentation of another antcn a ompr s t o po te d pol n td in accordance with the invention, using one such composite dip e c hef sho n. i IG- and e of thc c shown in FIG, 7.

Initially the invention will be explained in connection with thediagrams of FIGS. 1 through 5 inclusive, These figures illustrate theantenna elements discussed assimple lines and are to be considered asviewed from above, The mechanical connections of element to element andthe fastening means and insulators are for the most part omitted sincemany forms are possible.

As set forth hereinabove, a principal purpose of this invention is toimprove the high frequency harmonic response of the composite dipoleshown and described in [1.8. Patent 2,772,413 without in any wayimpairing the low frequency response thereof.

In FIG. 1 there is illustrated the end-fire composite dipole 10 of saidUS. patent, which is formed of three driven elements 12, 14 and 16resonant at some frequency in the high band of the television spectrum,say, for example, channels 11, 12 or 13. The dipole is also intended tobe resonant at some low band channel such as for example, channel 2. Therange is, of course, the greatest spread possible in the presenttelevision spectrum since channel 2, at the low end of the low band hasfrequencies from 54 to 60 megacycles per second, While channel 13 at thehigh end has frequencies from 210 to 216 megacycles per second. Theratio of the high and low channels is certainly not a whole number,which adds to the difliculties of ordinary harmonic operation.

As explained in said U.S. patent, there are also three parasiticelements 18, 20 and 22 provided, and diagonal connecting members 24 and26. The elements 12, 22 and 14 are collinear, but not electricallyconnected. The elements 18, 16 and 20 are also collinear and notelectrically connected, Instead, the elements 12 and 16 are c cd by alick Z8 and the e ements 1.4 a d 16 r c ctc y the k 30- The hh h l o thhalves of the element 16 are grounded to the boom (not shown) and theinner ends of the diagonals are connected to the transmission line 32.

The usual pattern obtained from this composite dipole 10 operating atsome high band frequency was generally as shown, comprising a relativelygood forward lobe L with two or more small minor lobes L rearward and ltc l y- 0 h low r que es h c cr, e in f the a e a d c as d, e pec allywh r only a single composite dipole was used for economy. The elements18 and 20, not always used, improved the pattern somewhat, but added tothe cost.

Thus, in said US. patent, several arrangements of composite dipoles wereassembled on booms, including one, two and three of the dipoles 10.Where there are several such dipoles, the loss in gain was not asnoticeable as where only one composite dipole was used, because thevarious dimensions could be easily adjusted for the various compositedipoles to encompass portions of the upper and lower bands of thespectrum. In a composite antenna which has three such assemblages, onewas constructed to resonate at channel 6 of the low band and channel 13of the high band; a second was constructed to resonate at channel 4 ofthe low band and channel 10 of the high band; and the third wasconstructed to resonate at channel 2 of the low band and channel 7 ofthe high band. In these composite dipoles, the ratio of high to lowfrequencies approached a whole number, giving fairly good results, butstill leaving room for considerable improvement.

The dimensions of these composite dipoles could bear study foremphasizing the problem here. The overall length of elements equivalentto 12, 22, and 14 for best resonance on channel 13 was found to beapproximately 66 inches, the distance between the front and rearcollinear elements being about 6 inches, and the length of the reardriven element equivalent to element 16 being approximately 21 inches.

On the other hand, the overall length of the elements corresponding tothe diagonal elements 24 and 26 for best resonance at channel 2 wasfound to be about 48.5 inches, each, making the total physical lengthfor channel 2 operation well over 96". Obviously compromises were madefor antennas which could only use one composite dipole, but at best theproblem was not satisfactorily solved in every case.

Consider now the end-fire array of FIG. 2. For satisfactory high bandoperation, the dimensions of the elements 12, 1.4, were found to bebetween 24 and 28 inches in length, emphasizing the more diflicult toreceive channelswnamely those at the upper end of the band. Startingfrom this point it is necessary to examine the efiects of such operationon the low band, especially the lowest end of the low band, such as forexample channel 2. (We omit elements 18 and 20, since the economicalversion of the antenna will not include them, and they will notseriously affect the discussion of the theory.)

In FIG. 3 there is illustrated a simple dipole 40 made up of collinearquarter-wave lengths 42 and 44 which is either driven for transmissionor exposed to high frequency signals for reception. (Only the latterwilll be considered herein, although the electrical effects will be thesame on transmission, not usually carried out on multiple frequencyantennas.) The radiation pattern for the antenna when operated on afrequency f at which the antenna is an electrical half wave in length isindicated by the two lobes front and rear shown in broken linesdesignated L This is of course a pattern in a horizontal plane since thepattern is symmetrical about the axis of the dipole 40, being a toroid,in free p ce- This pattern is of course not satisfactory for unidirc t eu we a c a t tcch i a y ccnccrncd i that Part u a o nt hctc- .T c atechniques for ren e ing thc d pcl d ectional? which n ud decreasing theangle between the halves of the same, to form V shaped configurations.

Consider now the effect of operating the antenna 40 as resonant for afrequency f which is a multiple harmonic of the frequency 35, such asfor example a third harmonic (f,=3f In this case, the antenna 40 isthree dipoles collinearly connected insofar as the higher frequency isconcerned, and the resulting radiation pattern, or polar diagram as itis sometimes referred to, is a well-known multiple lobe pattern,symmetrical front and rear. The most outstanding characteristic of thepattern is the existence of predominating lobes L, which are at an angle3 with respect to the dipole 40. This angle is of the order of 40 orso.There is usually a plurality of minor lobes symmetrically disposed frontand rear, designated by a general lobe L which has very littleconsequences.

The impedance of a simple dipole such as 40 at the transmission line 50is of the order of 70 ohms, and when operated on third or fourthharmonic frequencies, the impedance is of the same order. It is desiredfor best operation that the antenna have an impedance which approaches300 ohms, the characteristic impedance of most two-wire transmissionlines used in television reception, to prevent high VSWR on the line andto decrease losses.

Modifying the antenna of FIG. 3 so that the dipole 40 is in theconfiguration of a shallow V as shown at 40 in FIG. 4 with the halfdipole elements 42 and 44 forming an angle a which approximatelyapproaches twice the angle B results in great improvement. The forwardlobes L tend to build up providing a forward pattern similar to thatshown at L in FIG. 4. Obviously with suflicient angle a a point can bereached where the lobes of the halves lie on top of one another and thelobe L is more regularly teardrop in shape. The back end patterncomprises a multiplicity of minor lobes which com bine to form thegeneral pattern L Forming the dipole 40 to a V configuration results inthe following:

(a) While the response pattern of the antenna for the higher channels,such as channel 13, tends to be improved, the usual increase inimpedance for V configurations does not seem to be greatly manifest forthe high band channels.

(b) The characteristics of the antenna for broad band reception areimproved on the channels of the low band, especially in channels 2 to 6.

(c) The optimum angle a for maximum gain and best response pattern forfrequencies in the high band was found to be about 100 to 120 for adipole which was cut for normal resonance at channel 2.

(d) The optimum angle a for maximum gain and best pattern for the highband channels so decreases the physical aperture of the antenna actingon channel 2 (that is, decreases the area subtended normal to theincident wave), that the gain of the antenna for channel 2, and ofcourse, the other channels of the low band would suffer.

(e) An angle a was chosen at approximately 140 which gave best overallperformance, gain-wise and pattern-wise for all channels.

The combining of the high band elements of FIG. 2 with the V shapedconfiguration of FIG. 4 was accomplished (FIG. 5) in a novel manner. Thedesire for greater length of the diagonal halves of the low bandelements 42 and 44 and the lesser angle a resulted in the provision ofelectrical connections 52 and 54 respectively at the junctions of theoutboard ends of the elements 12 and 14 with the diagonal elements 42and 44. This gives rise to extended lengths 56 and 58 on the ends of thediagonal elements 42 and 44. As in the case of the composite dipole 10,the center of the element 16 is grounded to the boom (not here shown)and the antenna feeds into a transmission line 50 connected across theinner ends of the diagonal elements 42 and 44.

Note that the spacing between the element 16 and the axis of collinearelements 12, 14 and 22 may be chosen fairly independent of the physicaldimensions of the remainder of the composite dipole. Note also that theoverall length of the elements 42 and 44, including their respectiveextensions 56 and 58 is readily adjusted without any physicaldifficulties arising because of the connections Hand 54.

The folding problem is solved by means described shortly, but sufiice itto say at this point that the connections 52 and 54 are pivotal.

As may be understood from the above description the change of theconstruction of the composite dipole of the said patent from that shownat 10 in FIG. 1 to that shown at 60 in FIG. 5 was a great improvementbecause of the advantages achieved. It was discovered, however, that theadvantages are even better than contemplated by the combination of FIGS.2 and 4. The radiation pattern was vastly improved on the high bandchannels, as shown at L, in FIG. 5. The back lobes decreasedconsiderably. Gain on'channels 1'1, 12 and 13 was improved by as much as2db, on the 140 angle dipole using lengths resonant at channel 2 of thelow band. The impedance of the antenna on the high band channels wasalso increased.

None of the changes made had the efiiect of impairing the ability of theantenna to receive channel 2, which is a considerable achievement inview of the usual elfects of modifications made to low band antennas inattempting to make them resonant also to high band channels.

FIG. 6 illustrates a preferred manner of building a practical version ofthe antenna element described. The antenna is substantially the same asthat of FIG. 5, and hence will be designated 60. The element 22 isexemplified in a pair of half elements 22-L and 22-R each pivot allymounted at its inner end at 64 and 66 respectively, to a metallicbracket 68 suitably fastened to the boom 70. Likewise, element 16 isformed of halves 16-L and 16-R (left and right) pivotally secured attheir inner ends at pivots 72 and 74 respectively also upon a metallicbracket 76 which is mounted to the boom 70.

The outboard elements 12 and 14 have their outer ends return bent inbends 78 and 80 respectively, which are generally arranged in a verticalplane, each extending downwardly and engaging in the upper swivel half82 and 84 of the pivot junctions 52 and 54 respectively. In FIG. 6a thepivotal connection 52 is illustrated and it will be seen that the bottomswivel half 86 is secured to the left hand end of the diagonal element42. The extension 56 is beyond the pivotal connection 52. A pin 87'passes through all of the connected members and defines the swivel axis.

The inner ends of the elements 42 and 44 are mounted to a bracket 88which is insulated from the boom 70. The said inner ends are usuallyflattened and pierced, in a well-known technique, and engaged to saidbracket at 90 and 92 respectively by means of some fasteners such asthumb screws, so that the leads from a transmission line may beconnected thereto. Also, in disassembly, the element 42 and 44 may bedisconnected from the bracket 88 to enable folding of the compositedipole 60.

The outer ends of the members 22-L and 22R are provided with sleeveclamps 94L and 94R, short insulating rods 96-L and 96-R effectivelyconnecting the member 22 to the ends of the members 12 and 14respectively by similar sleeve clamps 98-L and 98-R. The links 28 and 30are pivotally connected between the clamps 98-L or 98-R and the ends ofthe members 16-L and 16-R, respectively.

It will be appreciated that the structure of the composite dipole 60provides substantial improvement over the composite dipoles of thepatent above referred to through several features, which, both combinedand individually result in improvements which were not obvious game fromthe original study of the dipole 10, for example, and the problems whichit was desired to solve. The placementrof the apex of the flat triangledefined by the elements 4'2, 44, 12, 22 and 14 a substantial distancerearward (considering the maximum, gain direction as the forward orfront end of the composite dipole) is important. It enables the angle ato be decreased substantially, without greatly affecting the gain on thelow end. The provision of the extensions 56 and 58 gave the benefits oflowband reception without materially detracting from the high bandreception which required the end-fire elements to be substantiallyshorter than the combined lengths of the low band dipole.

Obviously, the ability to be able to fold such an antenna is aconsideration for storage and transportation, and hence the use of theswivels or pivotal connections 52 and 54 contributed to the making ofthe antenna practical, because of its foldability.

The principles of the described composite dipole 60 are applicable in avariety of ways, and it was discovered that the use of structures ofthis kind on assemblages of composite dipoles resulted in greatimprovement over the assemblages of said Patent 2,772,413, which usedmore than one composite dipole. In other words, although the problemwhich it was desired to solve was originally intended to cover acomposite dipole which was to be used by itself in an antennaassemblage, the results discovered through the solution of this problemwere found admirably suited to the use of the structure for improvingantenna assemblages using two or more driven composite dipoles. Thebenefits were also applicable to antennas which used one or more drivendipoles of the composite structure of this invention, and one or moredriven dipoles of other structures. For example, one commercialstructure with which great success has been achieved, is an antennaassemblage which uses a composite dipole of a modified form togetherwith a folded dipole that is bent in a V configuration. This isillustrated in FIGS. 7 and 7a.

As to those antennas which use multiple composite dipoles, theadjustments for improved gain directivity over the entire televisionspectrum can be made using the principles of this invention with lessstringent requirements. The spectrum is not to be covered in onecomposite antenna, but is divided between two, three or even more suchdipoles. FIG. 8 illustrates one such structure using two compositedipoles.

Referring now to FIG. 7, the principles of the invention are applied toan assemblage of two driven dipoles, 100 and 102 to form an antenna 104of the so-called end-fire type. The forward composite dipole 100 isconstructed substantially like that of FIGS. 5 and 6 with one importantexception. The angle on of the dipole 100 is much greater than the sameangle of the dipole 60 and hence the spacing between the apex of thetriangle and the intersection of the element -16 with the boom 70 ismuch less. Economically, the boom has both the brackets 76 and 88 ofdipole 100 secured at the same point, by the same rivets or bolts. Anincrease in this distance over that of the dipole will improve theantenna characteristics because of the decreased angle a without damageto the response of the high band elements. In the composite dipole 60 asused in a practical antenna 110 in FIG. 8, the distance between theelement 22 and element '16 was increased from 6 inches of dipole -10 to8 inches. The distance from element 16 to the apex of the triangle(center of bracket 88 of FIG. 6) was 6 inches. In thecomposite dipole100 of FIGS. 7 and 7a the distance between elements 22 and 16 was chosenat 8 inches. Other antennas have been constructed in which the distancefrom element 16 to the apex of the triangle is more than 6 inches, andobviously, considerable latitude is feasible in this as well as otherdimensions.

The 'composite dipole :100 of antenna 104 is formed of the same elementsas those of composite dipole 60 and hence the same characters ofreference areapplied. Note that the directional aspectsof'EIGS. 7 and 6are reversed so that the forward direction foreach antenna is'represented by the large arrow alongside the respective booms 70. Thebrackets? 76 and 88 are mounted at the same position on the boom 70which in turn is clamped to a mast 112 by theusual U-bolt and clamparrangement shown at 114.

The back end ofthe antenna 104 has a folded dipole 102 which is formedof upper elements 112 and lower elements 114 connected at their outerends by reverse bends 116. The elements are arranged in a Vconfiguration for improved directivity and gain on the low band. Theinner ends of the elements 112 are pivotally mounted to the metallicbracket 118 which is secured to the boom. The inner ends of the elements.114 are pivotally mounted to the insulating bracket 120 which is alsomounted to the boom at the same place. An open wire transmission line122 is connected between the inner terminals of. the elements 114 andthe inner terminals of the elements 42 and 44, being provided along itslength with suitable insulating spacers 124. The length of thetransmission line is chosen to properly phase the dipoles 102 and 100 toenable their response to receive signals to reenforce one another, hencethe transmission line 122 comprises a phasing harness.

The signal produced by the. antenna 104 is remarkably good over bothbands of the television spectrum, only one parasitic director 126 beingused to reenforce the response on the .high band. The V configurationfolded dipole 102 on the back end of the antenna makes the antennahighly uni-directional, gives improved low frequency gain, renders theantenna compact. and easy to set up, provides good impedance match, andwhen combined with the composite dipole 10 0 takes care of thecompromises which are dictated in the construction of said dipole 100economically.

Spacing between driven composite dipoles of the antennas describedherein to achieve the desired end-fire operation is AM to 3x where 7& isthe center wave length of the low band and A the center wave length ofthe high band.

In order to enable those skilled in the art to appreciate that theantenna 104 is a remarkably small antenna to be effective for fringearea reception, dimensions of a commercial version are set forthhereinafter:

The total length of the boom 70 31 inches. Elements 112, 114 (Each halfprior to forming) 100% inches. Element 126 (overall) 26 inches. Element16 21 inches. Element 22 23% inches. Elements 12 and 14 (each) 23%inches. Insulators 96 2 inches.

Elements 42 and 44 (each) 41 inches. Distance bracket 118 to element 1269 inches. Distance element 126 to bracket 76 11 inches. Distance bracket76 to bracket 68 8 inches. Approximate end extension of boom 1 /2inches. Total length of transmission line -122 before forming 397/inches. Dipole 100 resonant at 70 mc. and 200-215 mc. Dipole 102resonant at 55 me. and 180 mc. Angle a for dipole 100 Approx. 155

The angle a for the folded dipole 102 is approximately to take advantageof the effect of forming the V. In order to achieve strength in the'dipole 102 each upper element 112 has a short straight portion 112' atits inner end which cooperates with spring locking structure of thebracket 118 to firmly aflix these inner ends. The spring lockingstructure of the bracket 118 is described in detail in said Patent2,772,413. The angle is then achieved by the slight bend at 112". Thelower element 114 has each inner end flattened and pierced to be engagedupon studs provided on bracket 120 and held in place with the terminalsof the phasing harness 122 and the transmission lead-in line 130 bymeans of washers and thumb nuts.

The upper and lower elements of the folded dipole 102 are not in aperfectly vertical plane, although substantially so. This, however,instead of being detrimental, is believed to broaden the response of therear end of the antenna, a characteristic greatly desired in thereception of color television. As shown in FIG. 7a, in top view theelements 112 and 114 diverge slightly from their ends inward, because ofthe structure described.- This provides substantial strength for theelement 102, as stated above, and yet enables the element to be foldedalongside of the boom, by disconnecting the inner ends of the parts 114and then pivoting the entire dipole about the connection with bracket118.

The antenna 110 is shown in FIG. 8 only diagrammatically, but itsconstruction should be readily perceived. The front end of the antennais provided with a suitable director 150 which is of the constructionshown and described in my copending application Serial No. 695,480 filedNovember 6, 1957 and entitled Parasitic Antenna Assemblage, now US.Patent 2,864,084.

The boom 70 of the antenna is substantially longer than the boom of theantenna 104 and greater gain and directivity are possible with thisantenna. Furthermore two of the composite dipoles are used, along withseveral parasitics. The element immediately behind the front enddirector 150 comprises a three element high band collinear director 152with the individual element connected mechanically, but notelectrically. The center element is of course mounted on a bracket (notshown) similar to bracket 68 of FIG. 7, and hence is metallicallyconnected to the boom.

The next rearward element of the antenna 110 is a driven compositedipole whose construction is practically identical to that of thecomposite dipole 100. In actual practice, the dimensions of the two arealmost identical, except for the length of the diagonal elements 42 and44. In the antenna 110 these elements are a fraction of an inch shorterthan the same elements of antenna 104.

The next rearward element of the antenna 110 is a driven compositedipole which is substantially identical in construction to the dipole 60of FIGS. and 6. Note the spacing between the element 16 and the apex ofthe triangle formed by elements 42, 44, 12, 22 and 14.

The two rear elements of the antenna are designated 154 and 156 andthese are low band reflectors.

The antenna 110 gives greater gain, band width, and directivity than anantenna constructed with the composite dipoles of FIG. 1, and this isespecially true on the channels of the high band.

The practical example of the antenna 110 was constructed with thefollowing dimensions:

Overall length of boom 70 (Approx.) 80 inches. Dimensons of director 15049' inches long, 6 inches along boom. Distance between director 150 andelement 152 6 inches. Overall length of element 152 73 inches.Individual elements 23 inches. Distance between element 152 andcomposite dipole 100 5 inches. Composite dipole 100 Same as previouslydescribed dipole 100, with very slight variations.

Distance between dipole I and dipole 60 8 inches. Dipole 60:

Elements 12, 14 26 inches. Elements 16, 22 24inches. Elements 42, 44 49%inches. Extended ends 56, 58 9% inches. Angle a Approximately Distance16 to 22 8 inches. Distance 16 to apex 6 inches. Distance apex of dipole60 to the reflector 154 22 inches. Both reflectors 154 and 156 110inches. Distance between reflectors 8 inches. Phasing harness, lengthbefore forming 33 inches. Dipole 60 resonant at 54-58 me. and me.

There can be no question that an antenna which is required to receiveall channels over the both bands of the television spectrum offrequencies must involve com promises, depending upon the extent towhich the antenna is resonant to the channels to be received. With thisinvention, it is believed that the minimum of compromise is required inantennas which have only one of two driven composite elements. Itfollows that applying the principles of the invention to an antennawhich uses three or four driven composite dipoles, it is practical tostagger tune the antenna for channels along the bands closely separated.The broad-banding character of the antenna will thus result in afrequency response, gain, and directivity which is substantially uniformfor all channels. Such antennas have been constructed and successfullytested.

Attention is especially invited to the frequency characteristics of thedipole elements 60 and 102. Note that the practical examples of dipole100 had a high frequency range of almost 15 megacycles which isremarkably broad. The practical example of dipole 60 had a low frequencyresonant range of about 4 megacycles. These resonant conditions arethose at which for all practical purposes the gain is practicallyconstant, and the effect is that for frequencies on either side of theresonant ranges, the gain drops off much less rapidly than in the caseof ordinary driven elements. It is therefore possible to build antennashaving unusually broad frequency characteristics without the need for agreat number of driven elements and modifying parasitic elements.

The impedance of the driven dipoles in the antennas described wasimproved over the usual dipole to provide close matches to the usual 300ohm transmission line almost universally used for the lead-in wire withprment television antennas.

It is believed that those skilled in the art will understand theinvention fully and realize that the structures illustrated are onlypreferred embodiments capable of wide variation. It is also desired topoint out that the invention is primarily directed to the reception oftelevision signals, and hence, structures which are described herein areresonant in the high frequency ranges of the present televisionspectrum. The principles of the invention, however, are applicable toother than the specific frequencies used for television in the UnitedStates today. Through dimensional modification the principles may beapplied to high frequency antennas operating in both lower and higherbands for multiple frequency reception. Conceivably the antenna could beused for transmission of multiple frequencies as well, but obviously itis not a usual practice to use this type of multiple resonant antennafor transmission of high frequency signals.

I claim: 1. A broad band composite dipole especially for the receptionof television signals and resonant at two fre- 11 r. quencies one ofwhich is approximately an odd multiple of the second frequencycomprising: at least four horizontally arranged short dipole elementseach of a length resonant at the first frequency, three of the elementsbeing collinear and mechanically connected, the fourth element beingspaced from the middle short element in a horizontal plane therewith andhaving its' ends electrically connected with the inner ends of theoutboard pair of said collinear elements, the middle short element beingparasitic, a pair of members forming a V-shaped dipole having a centerconnection with a transmission line and arranged in a V having its apexspaced rearward of the said middleshort element and having a lengthrendering same resonant generally at said second frequency, the outerends of said outboard pair having a metallic connection respectivelyadjacent the outer ends of said pair of members and there being asubstantial length of each of said pair of members extending outward ofsaid metallic connection. i

2. A structure as claimed in claim 1 in which said composite dipole ismounted on a horizontal boom arranged in the center of said compositedipole, the middle short element and the parasitic element are dividedin their centers and pivotally connected to said boom, the center of thepair of members forming said V-shaped dipole are removably andinsulatedly secured to said boom, and the said metallic connections arepivotal.

3. A structure as claimed in claim 1 in which the angle of said V isapproximately 100 to 155.

4. A structure as claimed in claim 1 in which the angle of said V isapproximately 140.

5. A structure as claimed in claim 1 in which the angle of said V issubstantially less than approximately 155 and the apex of said V isspaced rearwardly of said fourth short dipole element.

6. A broad band composite dipole mounted on a horizontal boom arrangedin the direction of maximum directivity of said antenna and comprising:four short dipole elements resonant generally to the same frequencymounted on the boom with three arranged collinearly and mechanicallyconnected end to end with the center one metallically secured to theboom and the fourth short dipole element in a horizontal plane andspaced rearwardly from the center short dipole element, but electrically connected with the outboard pair of short dipole elements, a longV-shaped dipole element resonant to a frequency which is approximatelyone-third the frequency of said short dipole elements, the inner ends ofthe halves of the V-shaped dipole element being mechanically mounted onsaid boom spaced a substantial distance rearward of the said fourthshort dipole element, but insulated from said boom, and the outer endsof the outer pair of said collinear short dipole elements metallicallyconnected therewith.

7. A composite dipole as claimed in claim 6 in which the said one andfourth short dipole elements are con nected to one side of the said boomand the said inner ends of said V-shaped dipole are mounted on theopposite side of said boom.

8. A composite dipole as claimed in claim 6 in which the said one andfourth short dipole elements are connected to one side of the said boomand the said inner ends of said V-shaped dipole are mounted on theopposite side of said boom, and the said outer ends have relativelyshort return bends and said metallic connections are provided by saidbends engaging with said V-shaped dipole in a plane slightly verticallyspaced from and substantially parallel with said first mentionedhorizontal plane.

9. A composite dipole as claimed in claim 6 in which the angle of saidV-shaped dipole is substantially less than approximately 155.

10. A composite dipole as claimed in claim 6 in which the angle of saidV-shaped dipole is approximately 140.

11. A broad band composite dipole mounted on a 12 horizontal boomarrangedin the direction of maximum directivity of said antenna andcomprising: four short dipole elements resonant generally to the samefrequency mounted on the boom with three arranged collinearly andmechanically connected endto end with the center one metallicallysecured to'the boom and the fourth short dipole element in a horizontalplane and spaced rearwardly from the center short dipole element, butelectrically connected with the outboard pair of short dipole elements,a long V-shaped dipole element resonant to a frequency which isapproximately one-third the frequency of said short dipole elements, theinner ends of the halves of the V-shaped dipole element beingmechanically'mounted on said boom spaced a substantial distance rearwardof the said fourth short dipole element, but insulated from said boom,and the outer ends of the outer pair of said collinear short dipoleelements metallically connected therewith at points spaced substantiallyinward of the free ends of said halves of said V-shaped dipole.

12. A substantially uni-directional antenna array which is formed of twodipole assemblages, each assemblage being arranged in substantially thesame horizontal level and being spaced from one another forsubstantially endfire operation, a common metallic boom defining thedirection of maximum directivity of the said array with the firstassemblage mounted at the forward end of said boom considering thedirection of maximum directivity' as forward, and the second assemblagebeing mounted at the opposite end thereof at the rear end of said boom,con sidering said rear end as pointed opposite the direction of maximumdirectivity, said first assemblage comprising a first dipole elementmounted at its center on the boom and metallically connected thereat,and having second and third collinear dipole elements respectivelyinsulatedly connected at the ends of the first dipole element and beingmechanically supported therefrom and forming outboard elements of acollinear grouping, a fourth dipole element spaced rearwardly from saidfirst dipole element and parallel therewith and metallically connectedat its center to said boom, a metallic connection between the outer endsof the said fourth dipole element and the respective inner ends of theoutboard elements, and a pair of rigid conductor elements arranged in aV-shaped configuration having their inner ends forming the apex of saidconfiguration and mounted upon said boom but insulated therefrom andfrom one another at a point spaced rearward of said first element withthe configuration diverging forward and the outer ends of said outboardelements metallically connected with said conductor elements, saidsecond dipole assemblage comprising a folded dipole arranged in V-shapedconfiguration diverging forwardfrom the end of said boom and spaced fromsaid first assembly by a maximum distance along saidboom of .1 thewavelength of the low band, each leg of the V being formed in asubstantially U-shaped configuration whose legs lie in a differentvertical plane, and are supported by said boom whereby said V-shapedconfiguration'is stabilized in a predetermined plane with respect to thefirst assemblage, phasing means connected between said folded dipole andthe inner ends of said pair of rigid conductors and means for connectingtransmission line means to said phasing means to drive said assemblages.

13. An antenna array as claimed in claim 12 in which said four dipoleelements are each resonant at approximately a first frequency,saidpair'of rigid conductors. is resonant at approximately a secondfrequency which is substantially one-third saidfirst frequency, and saidfolded dipole is resonant at approximately a third and a fourthfrequency which have a substantially three to one relation and saidthird and fourth frequencies being somewhat less than said first andsecond frequencies respectively. 7

V 14. An antenna array as claimed in claim 12 in which there is aparasitic elementmou'nted to said boom between said assemblages.

15. An antenna array as claimed in claim 12 in which said outer ends ofsaid outboard elements are connected to said conductor elements atpoints thereon spaced substantially inward of the ends of saidrespective conductor elements, whereby the effective electrical lengthof said pair of rigid conductors is substantially greater than threetimes the length of any one of said collinear dipole elements.

16. In an antenna array of the character described, which includes aboom having antenna elements thereon, a low band folded dipole at therear end of said boom and on one side thereof and comprising, a bracketmounted on said boom having a pair of oppositely extending rods securedthereto in metallic connection, each rod having a short section normalto the boom and a forwardly bent elongate section integral therewitharranged at an acute angle to the boom, a second bracket mounted on theopposite side of the boom at said rear end and having a second pair ofrods insulatedly secured thereto, said second pair of rods extendingoutwardly and forwardly from said boom each making an acute anglerelative to the boom slightly different from said first mentioned acuteangle, and the rod ends being joined in reverse bends with a respectiveone of said elongate sections whereby to form together a folded V-shapeddipole with the planes defined by the respective halves of said dipolemeeting along a line which extends downward and forward of said end ofsaid boom, said dipole serving as a reflector for the high band.

17. A structure as claimed in claim 16 in which the first pair of rodshas its inner ends independently pivotally mounted on said firstbracket, and said second pair of rods has its inner ends removablymounted on said second bracket, whereby upon removal of said inner endsof the second pair of rods, the halves of said folded dipole can becollapsed substantially parallel with said boom.

18. A broad-band substantially uni-directional antenna array which isformed of at least two dipole assemblages, each assemblage beingarranged on the same level and being spaced from one another forreenforcing operation at signals of two high frequency bands one ofwhich is generally three times the frequency of the other, a commonmetallic boom defining the direction of maximum directivity of saidarray, and each assemblage being mounted on said boom transverse thereofand each comprising, four dipole elements each resonant at a frequencyof said high band, the first of said four dipole elements beingparasitic and being metallically connected at its center to said boomand having the second and third dipole elements connected mechanicallyoutboard of said first element but insulated therefrom, the fourthdipole element being connected also at its center metallically with saidboom and parallel with and spaced rearwardly of said first element andhaving its ends electrically connected to the inner ends of said secondand third dipole elements, and a fifth element resonant generally at afrequency of said low band and comprising a substantially V-shapeddipole having its apex spaced rearwardly of said first dipole elementand its ends extending toward the ends of said second and third dipoleelements, engaging the same and extending substantially outward thereof,transmission line means connecting said dipole assemblages for phasedoperation, and one assemblage being of dimensions slightly greater thanthe other.

19. An antenna array as claimed in claim 18 in which at least one ofsaid dipole assemblages has its said apex spaced rearward of said fourthdipole element and the angle of said V-shaped dipole is between 100 and150.

20. An antenna array as claimed in claim 18 in which at least one ofsaid dipole assemblages has an angle of approximately 140 formed by itsV-shaped dipole.

21. A broad band composite dipole especially for the reception oftelevision signals and resonant at two frequencies one of which isapproximately an odd multiple of the second frequency comprising: atleast four horizontally arranged short dipole elements each of a lengthresonant at the first frequency, three of the elements being collinearand mechanically connected, the three collinear elements comprising apair of outboard elements and a middle short element, the fourth elementbeing spaced from the middle short element in a horizontal planetherewith and having its ends electrically connected with the inner endsof the outboard pair of said collinear elements, the middle shortelement being parasitic, a pair of members forming a V-shaped dipolehaving a center connection with a transmission line and arranged in a Vhaving its apex spaced rearward of the middle short element and having alength rendering same resonant generally at said second frequency, theouter ends of said outboard pair having a metallic connectionrespectively adjacent the outer ends of said pair of members and therebeing a substantial length of each of said pair of members, extendingoutward of said respective connection, each of said free ends of saidoutboard pair of short elements being return bent upon itself andengaging said V-shaped dipole at a point vertically spaced from the saidhorizontal plane, whereby the plane of said V-shaped dipole is slightlyspaced from and substantially parallel with said horizontal plane, butefiectively as though in the same plane therewith.

22. A broad band composite dipole especially for the reception oftelevision signals and resonant at two frequencies, one of which isapproximately an odd multiple of the second frequency comprising: atleast four horizontally arranged short dipole elements each of a lengthresonant at the first frequency, three of the elements being collinearand mechanically connected, the three collinear elements comprising apair of outboard elements and a middle short element, the fourth elementbeing spaced from the middle short element in a horizontal planetherewith and having its ends electrically connected with the inner endsof the outboard pair of said collinear elements, the middle shortelement being parasitic, a pair of members forming a V-shaped dipolehaving a center connection with a transmission line and arranged in a Vhaving its apex spaced rearward of the middle short element and having alength rendering same resonant generally at said second frequency, theouter ends of said outboard pair having a metallic connectionrespectively adjacent the outer ends of said pair of members and therebeing a substantial length of each of said pair of members extendingoutward of said respective connection, each of said free ends of saidoutboard pair of short elements being return bent upon itself andengaging said V-shaped dipole at a point vertically spaced from andsubstantially parallel with said horizontal plane, but efiectively asthough in the same plane therewith, each of said metallic connectionsbeing pivotal, there being a pin and a pair of engaged swivel members ateach connection, the pin passing through the pair of swivel members andeach swivel member having a crimp saddling one of the respectiveelements and members joined by said connections.

References Cited in the file of this patent UNITED STATES PATENTS2,531,035 Epstein Nov. 21, 1950 2,620,442 Trebules Dec. 2, 19522,624,001 Woodward Dec. 30, 1952 2,701,308 Kay Feb. 1, 1955 2,756,420Kolar et al. July 24, 1956 2,772,413 Guernsey et al. Nov. 27, 19562,789,286 Marshall Apr. 16, 1957

